Yeah, Mark's a great actor, but I could never picture him as Jim Carroll. Leo did a fantastic job, and he does look similar to what Jim Carroll looked like around that age. Mark played Mickey, who basiclly wasn't in the book as much as he's in the movie. I think he's mentioned like twice in the book, but I enjoyed the character of Mickey. Mark was good.

i think they did an amazing casting job. Leo did a great job as jim, and fit the part perfectly. his look and everything-kinda scrawny, tall, thin, his hair.
and Mark fit perfectly as Mickey. muscular and the big tough guy in the group._________________"It could of all been different Mr. Walker. You should of let nature take it's course...but in the end, it will anyway.
SO LET ME IN THE f*****g HOUSE!!"